1. Field of the Invention
The invention relates generally to a putter with a distance measurement mechanism.
2. Background Art
It is important for a player to have a good sense of distance to, at a first putt on the green, putt a ball in a one-putt range generally defined as a one-meter circle from a cup or hole. It is also important to putt the ball within the one-putt range with accuracy. A distance between the ball and the cup has been typically measured by visual measurement. Otherwise, the player may have paced off the distance. The visual measurement may allow a short distance to be accurately estimated. The player, however, would tend to fail to estimate a long distance due to a landscape opened out before the player. The measurement by pacing requires some practice, and thus the distance estimated by pacing is insufficient for common players. In addition, an inclination of the green is an important factor in putting. Thus, it is tough for the player with a few amount of practice to improve the player's skills of measurement because “swing back” motion for putting in accordance with the distance and inclination needs experience.
Japanese Patent Publication No. H7-289668 discloses a method using two laser beams irradiated from two devices disposed on a head of a putter. Specifically, the putter is positioned at the cup, and thereafter a first device of the putter irradiates a ball with a first laser beam in a direction perpendicular to a putting surface of the head. A second device, which is provided with a mechanism for adjusting a rotation angle, rotates such that a second laser beam irradiated from the second device is aligned with the point of the ball irradiated by the first laser beam, outputting the rotating angle. By way of this, the method allows the distance to the object to be calculated. However, the putter is expensive and requires long time during tense play.
Japanese Patent Publication No. H3-242161 discloses a device for measuring a distance between a point on through-the-green and a flagstick or pin. Specifically, a player holds a club away from the player's eyes at a predetermined distance, aligns a reference insignia for measurement disposed on the club with a top of the flagstick, thereby estimating the distance to the flagstick based on a position where an axis of a visual line to the flagstick intersects with the club. Its club head may be contact with a lie to stably hold the club, and the predetermined distance may be obtained by straightening the player's arm. The disclosed method measures the distance to the green, assuming that the length of the flagstick is two meters and the length of the arm is determined to a large extent by standard proportions of players. However, under the rules of golf, the flagstick should be taken out, and thus the method cannot be used on the green.
As mentioned above, the inclination of the green is one of important factors in putting with accuracy. Japanese Patent Publication No. 2001-286590 discloses measuring an inclination angle of the green and a direction to the cup. Specifically, a device disclosed in the publication includes a sphere container and a rolling element accommodated in the sphere container, and the angle can be measured based on a stationary state of the rolling element. However, the device lacks an angle scale on the container to determine degree of the inclination, and thus the device cannot accurately measure the inclination angle of the green.
Further, Japanese Utility Model Publication S53-50934 also discloses a similar device for measuring an inclination angle of the green and a direction to the cup. Specifically, the device includes a rolling element accommodated in a sphere container having an angle scale. The sphere container is filled with high-viscosity liquid. However, due to temperature characteristics of the liquid, error of measurement may occur. In addition, there may be a problem that the liquid leaks out.
As mentioned above, none of the conventional devices and methods can measure the distance to the cup with accuracy and with rapidity in atmosphere of tense play on the green.